Radiotracer and serial sectioning methods were used to study the diffusion of 65Zn, 59Fe and 63Ni isotopes in ferrites at temperatures of between 1130 and 1280C in air. In general, the diffusion profiles exhibited fast and slow regimes. In the case of slow diffusion, the diffusivities of Fe and Ni were similar while the diffusivity of Zn was higher. At temperatures below 1280C, the diffusion coefficients changed monotonically; depending upon the composition of the ferrite. In the solid solution, cation diffusion occurred much more slowly and with a higher activation energy than that in the case of the end-members. The results (table 69) indicated that, in Zn-containing ferrites, the cation diffusion was governed by the preliminary treatment which was given to the samples. In particular, the caking temperature had an effect upon the point defect concentration.

M.V.Slinkina, V.M.Zhukovskii: Izvestiya Akademii Nauk SSSR - Neorganicheskie Materialy, 1988, 24[11], 1883-6. (Inorganic Materials, 1988, 24[11], 1609-12)

Table 69

Diffusion Parameters for Fe, Ni and Zn in (Ni,Zn)Fe2O4 Ferrites

at Temperatures of between 1130 and 1280C